In my 647 square foot basement dedicated room on concrete slab, and concrete walls on threes sides, which is both; a listening room and home theater I did the following:
1. Joists (14” below floorboards) Spray foam 6 inches of high density
2. Roxul Safe and sound in all walls and ceiling
3. Resilient channel
4. Ceiling Quiet Rock sheet rock 530 5/8” and additional layer of quiet rock 510 1/2” installed opposite direction need long screws
4. Walls: quiet rock 530
5. back wall: double wall with Roxul safe and sound in each wall, and quiet rock 510 on each wall assembly front and back with a 1” space between the wall assemblies.
6. Green Glue on most drywall assemblies.
6. Solid wood door
7. Varied acoustic treatments / diffusion from GIK and vicoustic
8. Floor bamboo dark tone on slab with 4 in one adhesive, glue, noise and vapor barrier, and flexible.
The costs of the soundproof drywall will eat your budget. That is why I mixed 530 and 510 sheetrock.
Good luck
